1. Field of the Invention
This invention relates to liquid toluate-based ester compositions and their use as plasticizers, extenders or diluents in polymer formulations, a method of producing such ester compositions, as well as polymer compositions containing such liquid ester compositions. More particularly, this invention relates to the mono- or di-ester of methyl toluic acid with a diol containing 2 to 6 carbon atoms that are low viscosity liquids at 25° C. This invention also relates to the aforementioned esters modified with long chain hydrocarbon based extenders such as tall oil fatty acids or natural oils. The most common polymer that employs plasticizer is polyvinyl chloride (PVC). Typical amounts of plasticizer in PVC are from about 3 wt. % to about 50 wt. %. Phenolic resins generally require a hydrocarbon solvent/diluent/extenders that reduces the volatility and viscosity of the resin, especially when it is used in building or automotive products. Typical amounts of the aforementioned esters used as solvent/diluentlextender are from about 5 wt. % to about 65 wt. %.
2. Description of Prior Art
Esters derived from benzoic, substituted benzoic and toluic acid with aliphatic alcohols, and the methods for preparation, have been described in the prior art. These esters are primarily used as plasticizers for polymers to facilitate processing and increase flexibility and toughness. Homo- and co-polymers of polyvinyl chloride (PVC) account for the majority of the plasticizer usage. The most common plasticizer, dioctyl phthalate (DOP), has been the subject of negative environmental and toxicological studies and is a high cost additive. Benzoate plasticizers (dipropylene glycol dibenzoate, diethylene glycol dibenzoate) have been introduced as plasticizers but only have moderate compatibility with PVC.
U.S. Pat. No. 2,585,448 to Emerson et al. discloses mixtures of esters prepared by esterifying diols such as diethylene glycol, triethylene glycol with aromatic monocarboxylic acids such as benzoic acid and alkyl substituted benzoic acid. These esters are used as plasticizers.
U.S. Pat. No. 4,656,214 to Wickson discloses diesters having: 1) linear glycols containing from 2 to 8 carbon atoms, 2) a first carboxylic acid of the formula R1R2R3C(O)OH, and 3) a second carboxylic acid of the formula R5C(O)OH, wherein R1 and R2 are individually selected from alkyl containing from 1 to 4 carbon atoms, R3 is hydrogen or alkyl from 1 to 6 carbon atoms, R5 is selected from the group consisting of phenyl, mono- di- and trialkyl-substituted phenyl containing from 9 to 12 carbon atoms and —(CH2)nPh where Ph is phenyl and the value of n is from 1 to 6, inclusive. The esters contain from 16 to 19 carbon atoms and are useful as stain-resistant plasticizers for polyvinyl chloride.
U.S. Pat. No. 5,990,214 to Arendt et al. discloses liquid compositions of mixtures of esters derived from diethylene and triethylene glycol and benzoic or toluic acid. These esters are useful as plasticizers for PVC.
WO 02/083621 to Lang et al. discloses mixed esters prepared in a single step reaction from diols such as diethylene glycol, benzoic acid and an aliphatic acid such as lauric acid. These are liquid at room temperatures and are useful as plasticizers for PVC.
These ester compositions are still slightly volatile, and there is a need for ester compositions with lower volatility than commonly used materials such as dibutyl ester. Also these ester compositions are comparatively expensive and are still somewhat environmental sensitive and toxicological adverse. Thus there is a need for lower cost materials which are less environmentally sensitive and are not toxic.
Phenolic resins, including furan resins and phenolic urethanes, are used as binders for building products, wood products, insulation, foundry materials, abrasives and friction materials. In these formulations hydrocarbon solvents are used as diluents to reduce the viscosity of the phenolic resins. There is a need for diluents that have low volatility, or that can be incorporated into the resin, in order to reduce the Volatile Organic Compound (VOC) level. There is a need for diluents which produce low smoke in foundry applications.
U.S. Pat. No. 4,615,372 to Kopac et al describes a typical phenolic resin binder that contains 45-50 wt. % solvents, usually a mixture of aromatic hydrocarbons and moderately polar solvents.
U.S. Pat. No. 4,293,480 to Martin et al discloses a foundry binder based on a polyol, an isocyanate urethane polymer and a urethane catalyst. Again a polar solvent is used in this composition.
U.S. Pat. No. 6,291,550 to Chen et al discloses a solventless polyurethane no bake foundry binder, using polyether polyol, isocyanate and a urethane catalyst. In this invention, glycol such as triethylene glycol is used as a reactive diluent in the binder.
There is also a need for diluents and solvents that reduce the VOC level in other formulations such as paints, inks, elastomers, adhesives, foundry molding compositions, etc.
There is also a need for low viscosity dye carriers for textiles, polyurethanes, and paper applications which are more economical than existing carriers.